Currently, there is a need/trend to retrofit/replace those incandescent lamps in many types of existing navigational lighting systems with solid state lighting devices, e.g. light emitting diodes (LEDs). Yet it is desirable to keep the existing lighting fixture (lamp holder, electrical socket, mounting pole, etc.) since this is the most economical and quickest approach in considering that the existing lighting fixture is designed to comply with many standards/testing/certifications. A new LED lighting system with a totally new enclosure design will not only increase the cost, but also delayed the deployment of LED technology.
However, the existing lighting fixture is certainly not ideal for LED light sources. The main aspect of concern is thermal loading and heat dissipation. For LED light sources, the maximum junction temperature of the LED chip should not exceed 150° C. (degree Celsius). The existing lighting fixtures could not provide efficient heat dissipation means to maintain the LED temperature below this level because they are designed for incandescent lamps whose heat is dissipated through radiation means. Although there are numerous methods disclosed in the prior art for LED thermal management, e.g. U.S. Pat. Nos. 6,991,356, 7,144,135, 7,300,187, 7,329,030, 7,331,691, and 7,345,320, none of them could provide efficient LED cooling in a limited space as defined by the existing lamp holders. This is especially true when high intensity LEDs are employed, whose power consumption is 1-2 orders higher than that of conventional LEDs.
Hence is the purpose of the present invention to effectively address these issues.